well I guess i don't need to use that plastic ductwork as I have bought nothing yet. I am using it for my passive intake, just gonna have a 90 degree bend to keep light from getting in or out. I just thought if I used it for that I might as well use it for my exhaust as well. I may not need to use tubing at all for my exhaust but I thought that might be the only way to keep from letting light in or getting out of the exhaust hole. Wow I am learning so much from this site. You guys are great.